Popularity
Direct Marketing, by Katherine Adam, Radhika Balasubrahmanyam, and Holly Born, Appropriate Technology Transfer for Rural Areas (ATTRA). A broad over-view paper, very useful when first starting out. November 1999.

Direct Farm Marketing and Tourism Handbook, by Russell Tronstad and Julie Leones, Agricultural Resource Economics, University of Arizona, a web guide designed to help farm and ranch operators (and other individuals who grow or process food products) market their products and services directly to the consumer. Long, but very complete.

An Overview of Small Farm Direct Marketing. by M. E. Swisher, and James Sterns, University of Florida IFAS Extension.

Liability
The Legal Guide for Direct Farm Marketing, by Neil D. Hamilton, Professor of Law, Drake University, Des Moines, Iowa. One of the best guides on the subject.

Agritourism
Entertainment Farming & Agri-Tourism, by Katherine L. Adam, Appropriate Technology Transfer for Rural Areas (ATTRA).